I just want better control over the processor. I'd be happy with a modern processor, running at 10% clock speed and 50% voltage or less. I had a sony phone back

I just want better control over the processor. I'd be happy with a modern processor, running at 10% clock speed and 50% voltage or less. I had a sony phone back in the early days of android where after rooting I could actually tune the processor parameters, and I went from 1 to 4-5 days battery life. I haven't been able to find a way do it on my current phone due to lack of root. I don't care about having a super responsive phone, or a thin one. Just a utility. Something like the ulephone armor series but without the sketchy bloatware.